As a traveler, there’s a lot we don’t know about airplanes: why the windows are round, why the lights dim during landing and takeoff, and how do those tiny tires on the landing gear not pop when they hit the runway?

And, while we’ve explained all those quirks before, there’s one little aspect of an airplane seat, we’ve yet to reveal: the secret button that will turn your aisle seat into a spacious oasis. Ok, not exactly an oasis, but it will give you a little more room to breathe.

Where is this magical button, you ask? On the underside of the outer most armrest of the aisle seat (sorry, window seat-lovers, but you do get to rest your head against the window).

To find it, slide your hand under the armrest, close to the hinge and feel for the button. Press it and you are now free to move that armrest up so it’s flush with the back of your seat, giving you the freedom you deserve. A simple move with a big reward: no more armrest digging into your side and a little swing room for your legs.

It’s also a helpful trick to use at the end of your flight when you need more space to stand up and grab your luggage from the overhead bin. Instead of doing that awkward, half-backbend lean to grab your bag from above you, while also trying to avoid touching your neighbor, just put up the armrest and easily get out of your seat.

But, that’s not all this button was intended for. While it does provide some much-needed relief from the constricting boundaries of an airplane seat, its sole function isn’t to give you more room. It’s actually a safety measure to allow a quick and easy escape should you need to make an emergency exit from the plane.

So, on your next trip, make the move and choose the aisle seat. Go ahead and push that tiny button. Your sides will thank you, and you’ll probably blow the mind of your fellow passengers.

Related: Incredible photos taken by pilot from an airplane cockpit

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